Heavy vehicle brakes are known, for example EP1441142. Such brakes include a tappet assembly (in the case of EP1441142 two tappet assemblies) for applying a brake force to a brake pad. An operating shaft is rotatable about an axis which lies parallel to the brake disc plane. The operating shaft applies a force to one end of the tappet which in turn transmits that force to the brake pad. As the brake pads wear it is necessary for the length of the tappet to increase to compensate for the wear. An adjuster mechanism is provided to automatically adjust for brake pad wear. The adjuster mechanism is complicated since it has many components.